Studies show that saltmarshes excel at capturing carbon from the atmosphere. In this study, we measured CO₂ flux in an Australian temperate saltmarsh on French Island. The temperate saltmarsh exhibited strong seasonality. During the warmer growing season, the saltmarsh absorbed 10.5 g CO₂ m⁻² on average daily from the atmosphere. Even in winter, when plants were dormant, it continued to be a CO₂ sink, albeit a smaller one. Cool temperatures and high cloud cover inhibit carbon sequestration.